Liquid Crystal Display Luminance Control via Self-Calibration
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Solution Overview
Problem
Conventional liquid crystal display devices struggle to control luminance quantitatively due to variations in backlight luminance over time, leading to inconsistent gray-level characteristics and increased storage and measurement costs, as they rely on external photosensors for calibration.
Innovation Solution
A luminance control method that includes detecting the backlight's luminance, measuring the luminance of light emitted through the liquid crystal panel in various states, and calculating the desired luminance set value to control the backlight's luminance, allowing for precise luminance adjustment and gray-level characteristic realization without external photosensor measurements post-production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external photosensors are used for luminance measurement and calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The liquid crystal display device uses its own liquid crystal panel to perform luminance measurement functions. The liquid crystal panel can be controlled to display test patterns and measure luminance internally, eliminating the need for external photosensors. This self-service approach maintains measurement precision while reducing device complexity and cost.
Solution Approach 2:
The liquid crystal panel is designed to serve multiple functions: displaying normal images, performing luminance measurement, and conducting self-calibration. By making the liquid crystal panel universal and multi-functional, the patent eliminates the need for separate external measurement devices, thereby reducing overall system complexity while maintaining measurement capabilities.
2Device complexity
If backlight luminance is not controlled quantitatively, then device complexity is reduced, but manufacturing precision deteriorates due to variations over time
Solution Approach 1:
The patent implements a feedback mechanism where the liquid crystal panel continuously monitors its own luminance output and automatically adjusts parameters to maintain consistent gray-level characteristics. This internal feedback loop ensures manufacturing precision is maintained over time without adding significant device complexity, as the same liquid crystal panel performs both display and monitoring functions.
Solution Approach 2:
The liquid crystal panel performs preliminary self-calibration during the manufacturing process, storing calibration data internally. This preliminary action ensures that gray-level characteristics are precisely established before the device is shipped, compensating for potential variations without requiring complex real-time control systems.
3Measurement precision
If external photosensor measurements are performed post-production, then measurement precision is improved, but loss of time increases due to user burden
Solution Approach 1:
The liquid crystal panel performs all necessary luminance measurements and calibrations during the manufacturing process, storing the results internally. This preliminary action ensures that when the device is deployed, no additional calibration time is needed from users, eliminating the loss of time while maintaining high measurement precision through factory-performed calibration.
Solution Approach 2:
The device performs self-calibration automatically during manufacturing without requiring external photosensors or user intervention. This self-service approach during the production phase eliminates post-production calibration needs, thereby reducing the time burden on users while ensuring precise luminance characteristics are established.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables quantitative luminance control and superior gray-level characteristics by eliminating the need for external photosensor measurements, reducing user burden, and ensuring high accuracy in luminance settings, while allowing for individual wavelength band control for improved color reproducibility and white balance.
Implementation Method 1
controlling light transmittance determined by an electrooptical characteristic of a liquid crystal material
Implementation Method 2
luminance detecting means for detecting a luminance of the backlight
Data Source
AI summary
A luminance detected by a built-in photosensor and a luminance of light emitted from a backlight through a liquid crystal panel are measured in a plurality of states where the backlight has a different luminance, and are preliminarily stored in a storage unit. Moreover, a luminance of light emitted through the liquid crystal panel in each input level when the maximum luminance of light emitted through the liquid crystal panel is a predetermined value is measured and is preliminarily stored in the storage unit. The maximum luminance of light emitted through the liquid crystal panel is then accepted, the luminance of the backlight is controlled, the luminance in each input level and an ideal luminance in each gray level are calculated, and an input level which gives a luminance substantially equal to the ideal luminance in each gray level is obtained to update an LUT.